In the Republic of Congo, the reservoir pressures in the Likalala and Kombi fields have decreased since production start-up and have dropped below the bubblepoint resulting in secondary gas caps. Consequently, the producing gas/oil ratio (GOR) and gas void fractions (GVFs) of the wells have increased. These fields are produced using electrical submersible pumps (ESPs); however, the drawdown has been limited by traditional ESP gas handling technology, which typically cannot handle GVFs higher than 40%. Total E&P Congo installed three ESPs with advanced helicoaxial pump technology in these two reservoirs.

After nearly 2 years of operations on wells Likalala 106 and Kombi 102, production has stabilized and increased as a result of eliminating shutdowns and increasing drawdown. On the third well, Likalala 112, helicoaxial technology ensured that production targets were achieved despite unexpected high GOR and GVFs. This paper reviews these applications, focusing on the ESP and well outflow simulations, which demonstrate that the higher GVF handling capability of the pumps provides the technology needed to increase drawdowns. The paper includes analysis and review of well performance, from inflow through to facilities. It also reviews the in-situ GVF performance of the gas handling device with GVFs measurements as high as 80%.

A head correction correlation is also matched to the field results providing users with a method for modeling future ESP applications with high GVF. Finally the downhole gas separator efficiency is reviewed and suggestions made on how future completions can achieve higher separation efficiencies. The results are used to provide a benchmark and design guidelines for future high GOR-ESP applications.